Deformable diaphragm apparatus



July 30, 1963 E. BLONDIAU DEFORMABLE DIAPHRAGM APPARATUS Filed July 14.1960 INVEN TOR. 06420 5&0 0M0 ATTORNEY tatcs Q is 3,099,189 DEFORMABLEDIAPHRAGM APPARATUS Edgard Blondiau, Ile-St.-Denis, France, assignor toSociete STOP, Saint-Ouen, France, a corporation of France Filed July 14,196i), Ser. No. 42,879 Claims priority, application France Sept. 16,1959 4 Claims. (Cl. 9223) The present invention relates to fluidreservoirs for feeding hydraulic circuits, notably those of brakingsystems for vehicles, and it is the specific object of this invention toprovide a deformable diaphragm for isolating from the atmosphere or thesurrounding medium a reserve of fluid feeding a hydraulic system,notably the hydraulic control circuit of :the braking systems ofvehicles.

The diaphragm forming the subject-matter of this invention is intendedmainly for avoiding the contamination of the fluids utilized inhydraulic transmissions which are hydrophilic, as a rule.

The hydrophilic character of these fluids tends to alter their state anddue to this fact their physical properties are modified to a verysubstantial extent according to the percentage of water absorbedthereby. The presence of this absorbed water reduces more particularlytheir boilpoint as well as their resistance to oxidation by hydrolysis.

The hydrolysis phenomenon is not controllable in spite of the additionof buifer agents to the fluids with a view to impart stability andcorrosion-resisting properties thereto.

The consequences of this hydrolysis become apparent with time but itgenerally entails immediate disadv-an tages of lesser importance such asthe reduction in the boiling point of the fluid utilized.

Reports on research works concerning the modifications brought by theabsorption of water by the fluids utilized in hydraulic braking systemshave repeatedly been published.

These results have been discussed and criticized notably in automobiletechnical papers.

The conclusions to which these studies have led do not meet completelythe conditions set up with a view to finding a satisfactory solution tothis problem, for in spite of the adoption of fluids having a very highboiling point their contamination by water still remains the cause ofmajor disadvantages such as the reduction of the boiling point and thehydrolysis of the fluid, which results in a systematic corrosion of allthe component elements of the system.

By using the diaphragm constituting the subject-matter of the presentinvention it is possible to isolate completely from the atmosphere andthe surrounding medium the reserve of fluid in the system and to preventit from becoming contaminated by water from the outside.

This isolation is effected in an elastic manner so that the fluid levelin the reserve space may follow the variations in the requirements ofthe control circuits.

Accordingly it is an object of the invention to provide a deformablediaphragm for use in a fluid reservoir system which will followvariations in the fluid level of the reservoir while isolating the fluidtherein from contaminants outside the system.

It is a further object of the invention to provide an elastic diaphragmcapable of exerting pressure on the reservoir system.

It is a still further object to provide a deformable iaphragm for afluid reservoir system with a withdrawal rod communicating with theinterior of said diaphragm.

The above and further objects of the invention will be betterappreciated from the following specification and claims read inconjunction with the following drawing.

The single FIGURE of the attached drawing illustrates in diagrammaticaxial section a fluid reservoir provided with an elastic diaphragmaccording to this invention which, in the example illustrated, is abellows or like member having an accordion-like structure.

Referring to the drawing, it will be seen that the bellows-shapeddiaphragm 1 is mounted in :a conventional fluid reservoir 2 for feedinga hydraulic braking system (not shown) through connecting pipe 2a whichcommunicates with the reservoir at the bottom and which is fastenedthereto by a suitable pipe coupling 212, this reservoir being adapted tocontain the fluid reserve which the diaphragm contacts with its outersurf-ace.

The upper portion of this resilient bellows comprises an outwardlydirected flange 3 constituting a fluid tight sealing joint or gasketbetween a cover 4 and the upper edge of the reservoir 2. 'Dhis cover 4may be secured on the reservoir by screwing or otherwise.

The bottom portion of diaphragm 1 is formed with an integrally mouldedinner central boss 5 having fitted.

therein the head of a central rod 6. This rod 6 slides freely through acentral orifice 7 formed in the cover 4.

The upper portion of the central rod 6 emerges from the cover 4 and maycarry marks indicating the level of the fluid contents in the reservoirsince the bottom of the bellows 1 contacts the fluid in the reservoir.

The main function of the central rod 6 is to permit the withdrawal ofdiaphragm 1 upon the filling of the reservoir and, upon completion ofthis operation, the fitting of the cover 4 is replaced on the reservoir2.

To permit the fitting of the cover 4 on the reservoir 2 after the latterhas been filled with fluid, it is necessary that the deformablediaphragm 1 does not exert any piston-like thrust upon the liquidsurface before the flange 3 has actually sealed the joint between thereservoir and the cover.

To this end, the rod 6 may be provided with a circular groove or notch 9for retaining and positioning the diaphragm or bellows 1 in itsuppermost position 8 as shown in broken lines in the drawing, whereinthe bellows is folded and located close to the cover 4. Thus, when thebellows 1 is compressed, the groove or notch 9 is flush with the upperface of the cover 4.

A retaining pin or circlip 9' is threaded in the groove 9 and is adaptedto hold the bellows 1 in its compressed condition during the fitting andremoval of the cover 4 with respect to the reservoir for performing thefilling operation.

Upon completion of this filling operation, the pin or circlip 9' isremoved or slipped upward toward the upper end of rod 6, the latterbeing formed if desired with another groove or notch 10 for receivingthe retaining pin or circlip. It will be apparent that a maxi-mum amountof fluid may be introduced into the vessel 2 because of the minimumamount of fluid displaced by the diaphragm in its deformed positionafter replacement of the cover 4 over the vessel.

The essential function of the bellows 1 is to follow the liquid levelaccording to the demand from the hydraulic circuits connected to thereservoir 2.

This bellows may be made from any suitable flexible or resilientwaterproof material. Thus, elastic rubber or polyvinyl chloride may beused, but other suitable materials known to those skilled in the art mayalso be used.

The bellows 1 may also be provided with an inner loading spring. Thisspring may be placed within the space 11 communicating with theatmosphere through the orifice 7 formed in the cover 4.

Another solution to the problem of producing a load effect by means of abellows 1 consists in utilizing materials adapted to impart resilientproperties to this bellows 1 while creating a hydrostatic pressure onthe diaphragm by the liquid contained in the reservior 2.

This pressure is determined by the resilient properties of the bellows 1and may be utilized with the maximum efficiency in the hydraulic controlcircuits of automobile braking systems.

The presence of a column of liquid under pressure in the brake controlcircuit constitutes a valuable factor for the pressure maintenance ofthe proper fluid-tightness of the seals and packings in the circuit soas to prevent the undesirable ingress of air and the water-contaminationof the circuit.

Of course, the present invention should not be construed as beinglimited to the arrangement of a bellows in the fluid reservoir, for anydeformable diaphragm having the requisite elastic and sealing propertiesmay be used in lieu thereof.

While I have described above the principle of my invention in connectionwith specific apparatus, it is to be clearly understood that thisdescription is made only by way of example and not as a limitation tothe scope of my invention.

What is claimed is:

1. Filling and isolating apparatus for a hydraulic system comprising afluid reservoir vessel having :an output port in communication with saidhydraulic system, a deformable diaphragm adapted to fit within the bodyof said vessel and to exert pressure on the fluid in said vessel, aremovable cover :for the top of said vessel, said cover being providedwith a central aperture extending therethrough, said diaphragmcomprising :a bellows having an open end and a closed end, said open endhaving an outwardly extending flange adapted to be retained in hermeticsealed relation between the lip of said vessel and the inside of saidcover, a rod fastened to the inside of the closed end of said bellows,said rod adapted to extend through the aperture in said cover, a slot insaid rod running in a direction normal to the longitudinal axis of saidrod, and restraining means adapted to be fitted Within said slot aftersaid rod has been partially drawn through said cover in a directionopposite from the interior of said vessel, whereby to temporarilymaintain said diaphragm in deformed position against the inside portionof said cover when said cover is removed from said vessel so that thevolume of fluid which may be introduced into said vessel is subject tominimum displacement by said diaphragm after such introduction and thereplacement of said cover over said vessel.

2. Apparatus as claimed in claim 1, wherein said rod is circular incross section and the slot therein is radial and extendscircumferentially therearound.

3. Apparatus as claimed in claim 1, wherein said vessel and said bellowsare circular, said bellows being made of a resilient material and havingan outside diameter in either its normal or deformed positionssubstantially equal to the inside diameter of said vessel.

4. Apparatus as claimed in claim 1 wherein the slot in said rod ispositioned along the length thereof at a distance :from the bottom endof said diaphragm equal to the length of said diaphragm in its maximumdeformed position.

References Cited in the file of this patent UNITED STATES PATENTS1,174,232 Copeland Mar. 7, 1916 1,541,187 Ropte June 9, 1925 1,691,441Kennedy et :al. Nov. 13, 11928 1,905,583 Giesler Apr. 25, 1933 2,315,212Kron'miller et al. Mar. 30, 1943 2,939,471 Fay June 7, 1960-

1. FILLING AND ISOLATING APPARATUS FOR A HYDRAULIC SYSTEM COMPRISING A FLUID RESERVOIR VESSEL HAVING AN OUTPUT PORT IN COMMUNICATION WITH SAID HYDRAULIC SYSTEM, A DEFORMABLE DIAPHRAGM ADAPTED TO FIT WITHIN THE BODY OF SAID VESSEL AND TO EXERT PRESSURE ON THE FLUID IN SAID VESSEL, A REMOVABLE COVER FOR THE TOP OF SAID VESSEL, SAID COVER BEING PROVIDED WITH A CENTRAL APERTURE EXTENDING THERETHROUGH, SAID DIAPHRAGM COMPRISING A BELLOWS HAVING AN OPEN END AND A CLOSED END, SAID OPEN END HAVING AND OUTWARDLY EXTENDING FLANGE ADAPTED TO BE RETAINED IN HERMETIC SEALED RELATION BETWEEN THE LIP OF SAID VESSEL AND THE INSIDE OF SAID COVER, A ROD FASTENED TO THE INSIDE OF THE CLOSED END OF SAID BELLOWS, SAID ROD ADAPTED TO EXTEND THROUGH THE APERTURE IN SAID COVER, A SLOT IN SAID ROD RUNNING IN A DIRECTION NORMAL TO THE LONGITUDINAL AXIS OF SAID ROD, AND RESTRAINING MEANS ADAPTED TO BE FITTED WITHIN SAID SLOT AFTER SAID ROD HAS BEEN PARTIALLY DRAWN THROUGH SAID COVER IN A DIRECTION OPPOSITE FROM THE INTERIOR OF SAID VESSEL, WHEREBY TO TEMPORARILY MAINTAIN SAID DIAPHRAGM IN DEFORMED POSITION AGAINST THE INSIDE PORTION OF SAID COVER WHEN SAID COVER IS REMOVED FROM SAID VESSEL SO THAT THE VOLUME OF FLUID WHICH MAY BE INTRODUCED INTO SAID VESSEL IS SUBJECT TO MINIMUM DISPLACEMENT BY SAID DIAPHRAGM AFTER SUCH INTRODUCTION AND THE REPLACEMENT OF SAID COVER OVER SAID VESSEL. 